Morphology

The glow worm, Lampyris noctiluca, is actually a beetle in the insect family Lampyridae meaning "shining ones" in Greek. This family also includes other glowing species. Although Lampyris noctiluca is often referred to as a glow worm, it isn't worm-like at all. Other names that you may have heard for the Lampyridae family in general are fireflies and lightning bugs. Lampyris noctiluca is usually brownish to blackish in color. The adult female is 12-20 mm long, while the males are much smaller. The larvae are often only a few milimeters long. (Borror & White 1970; Scagell 1994; Tweit 1999)

The males possess two pairs of wings, but use only the second pair for flying. The first pair of wings, the elytra, form a cover over the second pair. The females do not fly. (World Book 1998)

They are soft-bodied and elongated. Their head is concealed from above by a pronotum, and their antennae are threadlike. Only the last few abdominal segments are luminous. (Borror & White 1970)

The adult female is the one responsible for the most active glowing although the larva, which is very similar to the female in respects, also glows. The male may glow slightly but is very different from the female who uses her glowing organs to attract and stimulate the male. Larvae glow much more faintly, and only intermittently, for a few seconds at a time. They are also not worm-like but have segmented bodies and six legs at the head end, quite similar to adults. However, when they help themselves along with their tails, they do appear a bit like caterpillars. (Alliston 1998; Scagell 1994)